The present invention relates to manual winches. More specifically, the present invention relates to a load release system for a manual winch.
1. Background Information
Winches have been used in many applications. Manual winches have been widely used in barges, tow boats and the like. Examples of manual winches are sold by W. W. Patterson Company and Nashville Bridge Company. The most common type of manual winch includes a pivotable pawl, or dog, engaging a ratchet gear of a ratchet for the winch. The pawl prevents the unwinding of the reel during engagement of the pawl.
It has been known to provide a pawl releasing system for disengaging the pawl to allow for unwinding the reel, also known as paying out the load. One known load release system includes a lever for pivoting the pawl out of engagement with the associated ratchet gear. The lever is designed to rest in an over-center position when the pawl is engaged, such that the force on the pawl is also forcing the lever to a closed position due to the over-center positioning. This design prevents the load on the ratchet gear from pushing the pawl to the disengaged position. This design has several difficulties. First, in releasing the pawl, typically after a separate brake has been set, the operator must overcome the load on the pawl due to the over-centering positioning of the lever. Under heavy loads, this can be difficult. Additionally, once the lever passes the center position, the force on the pawl will now be pushing the lever to the open disengaged position. This can result in a rapid movement of the lever which can possibly be injurious to the operator. Another drawback of this design is that the relative position of the elements essentially requires the distal end of the lever to be positioned near the ground in the locked position making it difficult to reach by the operator. The inaccessibility also results in the operator pulling on the lever in an awkward, uncomfortable position. The present invention is intended to provide a manual winch with a safe load releasing system which obviates the above discussed problems of the prior art.
The objects of the present invention are achieved by a manual winch having a safe load releasing system according to the present invention. The manual winch includes a housing supporting a rotatable reel, a ratchet assembly coupled to the reel movable between an engaged and disengaged position wherein the reel is rotatable only in one direction when the ratchet assembly is in an engaged position, and a load releasing system for moving the ratchet assembly system to a disengaged position. The ratchet assembly includes a rotatable ratchet gear which is adapted to be engaged by a pivotable locking pawl. The locking pawl is pivotable into and out of engagement with the ratchet gear for moving the ratchet assembly between the engaged and disengaged position. The locking pawl is mounted on a movable base which secures the locking pawl to the housing. The load releasing system includes a linear mechanical actuator for moving the relative position of the base relative to the ratchet gear and the housing, and a separate brake for holding the reel and ratchet gear in position under a load.
In operation, when the winch is under load and the user desires to pay out or unreel a portion of the rope, the winch according to the present invention operates as follows. First, the brake, typically a hand brake, is tightened to secure the reel and ratchet gear in position before the pawl has been released. After the brake has been tightened, the actuator moves the base relative to the housing and the ratchet gear such that the associated pawl is moved relative to the ratchet gear and the housing. The movement of the base will transfer the load from the locking pawl to the tightened brake. Once the load has been fully transferred, the pawl can be easily pivoted out of engagement to the disengaged release position and the brake can be released to pay out the load as desired.
In the preferred embodiment of the present invention, the linear actuator is a manual jack screw operated by a hand wheel located near the top of the winch. The base can be easily formed as a pivoted linkage arm extending from the ratchet gear shaft with the brake being a conventional friction hand brake.
Another aspect of the present invention is that the present invention accommodates resetting if the brake is not set before transfer. A further feature of the present invention is the retrofitting of existing winches with the load release system of the present invention.
Another embodiment of the present invention provides for automatic pivoting of the pawl to a disengaged position as the base is moved. A stop may be positioned to engage the pawl as the base is lowered such that further lowering of the base will case the pawl to be pivoted away from the ratchet gear due to the engaged stop.
These and other advantages of the present invention will be clarified in the brief description of the preferred embodiments taken together with the attached figures wherein like reference numerals represent like elements throughout.